[polly] r288479 - [ScopInfo] Separate construction and finalization of memory accesses [NFC]
Tobias Grosser via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 1 21:21:22 PST 2016
Author: grosser
Date: Thu Dec 1 23:21:22 2016
New Revision: 288479
URL: http://llvm.org/viewvc/llvm-project?rev=288479&view=rev
Log:
[ScopInfo] Separate construction and finalization of memory accesses [NFC]
After having built memory accesses we perform some additional transformations
on them to increase the chances that our delinearization guesses the right
shape. Only after these transformations, we take the assumptions that the
array shape we predict is such that no out-of-bounds memory accesses arise.
Before this change, the construction of the memory access, the access folding
that improves the represenation for certain parametric subscripts, and taking
the assumption was all done right after a memory access was created. In this
change we split this now into three separate iterations over all memory
accesses. This means only after all memory accesses have been built, we start
to canonicalize accesses, and to take assumptions. This split prepares for
future canonicalizations that must consider all memory accesses for deriving
additional beneficial transformations.
Modified:
polly/trunk/include/polly/ScopInfo.h
polly/trunk/lib/Analysis/ScopInfo.cpp
Modified: polly/trunk/include/polly/ScopInfo.h
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopInfo.h?rev=288479&r1=288478&r2=288479&view=diff
==============================================================================
--- polly/trunk/include/polly/ScopInfo.h (original)
+++ polly/trunk/include/polly/ScopInfo.h Thu Dec 1 23:21:22 2016
@@ -643,8 +643,7 @@ private:
/// The introduction of different cases necessarily complicates the memory
/// access function, but cases that can be statically proven to not happen
/// will be eliminated later on.
- __isl_give isl_map *foldAccess(__isl_take isl_map *AccessRelation,
- ScopStmt *Statement);
+ void foldAccessRelation();
/// Create the access relation for the underlying memory intrinsic.
void buildMemIntrinsicAccessRelation();
@@ -1876,7 +1875,7 @@ private:
/// @param R The region we build the statement for.
void addScopStmt(Region *R);
- /// @param Update access dimensionalities.
+ /// Update access dimensionalities.
///
/// When detecting memory accesses different accesses to the same array may
/// have built with different dimensionality, as outer zero-values dimensions
@@ -1885,6 +1884,30 @@ private:
/// the dimensionality of the underlying ScopArrayInfo object.
void updateAccessDimensionality();
+ /// Fold memory accesses to handle parametric offset.
+ ///
+ /// As a post-processing step, we 'fold' memory accesses to parameteric
+ /// offsets in the access functions. @see MemoryAccess::foldAccess for
+ /// details.
+ void foldAccessRelations();
+
+ /// Assume that all memory accesses are within bounds.
+ ///
+ /// After we have built a model of all memory accesses, we need to assume
+ /// that the model we built matches reality -- aka. all modeled memory
+ /// accesses always remain within bounds. We do this as last step, after
+ /// all memory accesses have been modeled and canonicalized.
+ void assumeNoOutOfBounds();
+
+ /// Finalize all access relations.
+ ///
+ /// When building up access relations, temporary access relations that
+ /// correctly represent each individual access are constructed. However, these
+ /// access relations can be inconsistent or non-optimal when looking at the
+ /// set of accesses as a whole. This function finalizes the memory accesses
+ /// and constructs a globally consistent state.
+ void finalizeAccesses();
+
/// Construct the schedule of this SCoP.
///
/// @param LI The LoopInfo for the current function.
Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=288479&r1=288478&r2=288479&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
+++ polly/trunk/lib/Analysis/ScopInfo.cpp Thu Dec 1 23:21:22 2016
@@ -477,8 +477,6 @@ void MemoryAccess::updateDimensionality(
}
isl_space_free(ArraySpace);
-
- assumeNoOutOfBound();
}
const std::string
@@ -738,8 +736,10 @@ void MemoryAccess::computeBoundsOnAccess
AccessRelation = isl_map_intersect_range(AccessRelation, AccessRange);
}
-__isl_give isl_map *MemoryAccess::foldAccess(__isl_take isl_map *AccessRelation,
- ScopStmt *Statement) {
+void MemoryAccess::foldAccessRelation() {
+ if (Sizes.size() < 2 || isa<SCEVConstant>(Sizes[1]))
+ return;
+
int Size = Subscripts.size();
for (int i = Size - 2; i >= 0; --i) {
@@ -785,7 +785,15 @@ __isl_give isl_map *MemoryAccess::foldAc
MapOne = isl_map_union(MapOne, MapTwo);
AccessRelation = isl_map_apply_range(AccessRelation, MapOne);
}
- return AccessRelation;
+
+ isl_id *BaseAddrId = getScopArrayInfo()->getBasePtrId();
+ auto Space = Statement->getDomainSpace();
+ AccessRelation = isl_map_set_tuple_id(
+ AccessRelation, isl_dim_in, isl_space_get_tuple_id(Space, isl_dim_set));
+ AccessRelation =
+ isl_map_set_tuple_id(AccessRelation, isl_dim_out, BaseAddrId);
+ AccessRelation = isl_map_gist_domain(AccessRelation, Statement->getDomain());
+ isl_space_free(Space);
}
/// Check if @p Expr is divisible by @p Size.
@@ -858,9 +866,6 @@ void MemoryAccess::buildAccessRelation(c
AccessRelation = isl_map_flat_range_product(AccessRelation, SubscriptMap);
}
- if (Sizes.size() >= 2 && !isa<SCEVConstant>(Sizes[1]))
- AccessRelation = foldAccess(AccessRelation, Statement);
-
Space = Statement->getDomainSpace();
AccessRelation = isl_map_set_tuple_id(
AccessRelation, isl_dim_in, isl_space_get_tuple_id(Space, isl_dim_set));
@@ -3090,6 +3095,12 @@ Scop::Scop(Region &R, ScalarEvolution &S
buildContext();
}
+void Scop::finalizeAccesses() {
+ updateAccessDimensionality();
+ foldAccessRelations();
+ assumeNoOutOfBounds();
+}
+
void Scop::init(AliasAnalysis &AA, AssumptionCache &AC, DominatorTree &DT,
LoopInfo &LI) {
buildInvariantEquivalenceClasses();
@@ -3122,7 +3133,8 @@ void Scop::init(AliasAnalysis &AA, Assum
buildSchedule(LI);
- updateAccessDimensionality();
+ finalizeAccesses();
+
realignParams();
addUserContext();
@@ -3208,6 +3220,18 @@ void Scop::updateAccessDimensionality()
Access->updateDimensionality();
}
+void Scop::foldAccessRelations() {
+ for (auto &Stmt : *this)
+ for (auto &Access : Stmt)
+ Access->foldAccessRelation();
+}
+
+void Scop::assumeNoOutOfBounds() {
+ for (auto &Stmt : *this)
+ for (auto &Access : Stmt)
+ Access->assumeNoOutOfBound();
+}
+
void Scop::simplifySCoP(bool AfterHoisting) {
for (auto StmtIt = Stmts.begin(), StmtEnd = Stmts.end(); StmtIt != StmtEnd;) {
ScopStmt &Stmt = *StmtIt;
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